1. Field
This specification relates to a refrigerating cycle apparatus and a method for operating the same, and particularly.
2. Background
In general, a refrigerating cycle apparatus may employ a compressor, a condenser, an expansion apparatus and an evaporator to keep an inside of a refrigeration device such as a refrigerator at a low temperature. The refrigerating cycle apparatus may use oil to protect the compressor from mechanical friction. The oil may circulate in the refrigerating cycle mixed with high temperature and high pressure refrigerant gas discharged from the compressor.
When the oil is accumulated in the condenser or evaporator of the refrigerating cycle or pipes connecting various elements of the cycle, a capability of the refrigerating cycle may be degraded and result in a lack of oil in the compressor, thus damaging the compressor.
In a refrigerating cycle having a single compressor, an amount of collected oil may be known based on a speed at which refrigerant is collected and flows back into an inlet. Hence, an operation of the compressor may be controlled based on the amount of oil collected so as to prevent degradation of the capability of the refrigerating cycle damage to or the compressor due to the lack of oil.
In a refrigerating cycle having a plurality of compressors, refrigerant and oil may be concentrated in one compressor based on a particular driving mode. This may cause a lack of oil in the other compressors, thereby degrading the capability of the refrigerating cycle and/or causing damage to the compressor(s).
In such a refrigerating cycle apparatus having a plurality of compressors connected to each other, during the refrigerating cycle, oil filled in each compressor may be discharged from the compressors into the refrigerating cycle together with refrigerant. This may cause an oil unbalance between the compressors. Especially, when the plurality of compressors are connected in series so as to perform a multi-stage compression of a refrigerant, a different amount of oil flows in each compressor. Accordingly, oil may be concentrated in one compressor, and the other compressors may consequently suffer from an insufficient amount of oil. This may result in a frictional loss and an increase in power consumption.
Furthermore, in a refrigerating cycle apparatus having a plurality of compressors, when an oil balancing container is separately installed at outside of the compressors in order to address the oil unbalance between the compressors, an amount of space occupied by the compressor(s) is increased due to the installation of the oil balancing container and pipes, which may have a complicated structure, increasing flow resistance and lowering cooling efficiency.